The New York Times called the skeleton crews of workers and soldiers inside the plants "perhaps Japan's last chance of preventing a broader nuclear catastrophe." But those who study radiation treatment and mitigation say there's not much these workers can do to protect themselves. "There are no proven radioprotectants [for workers] at this point," although some are being studied in animals, says David Weinstock, a bone marrow transplant doctor at Dana-Farber Cancer Institute in Boston. Weinstock is part of a group called the Radiation Injury Treatment Network (RITN).

Although widely talked about, potassium iodide pills are most useful for children and nursing mothers trying to prevent the intake of radioactive iodine, which is most often taken up when drinking contaminated milk or eating dairy products. That's what happened after Chernobyl. An intravenous drug, amifostine, could theoretically help, says Nelson Chao, also a member of RITN and the head of the division of cellular therapy and bone marrow transplants at Duke University in Durham, North Carolina. It was developed to protect cancer patients during radiation treatment and is now rarely used. But Chao says, "There isn't any data as to how" it might be offered, especially because it can't be taken by mouth.

The best shield is minimizing the dose of radiation and limiting the time exposed as much as possible. Wearing protective clothing and masks or respirators, as the Japanese workers are doing, can help them avoid particulate matter or radioactive dust, says Norman Kleiman, a radiobiologist who studies radiation exposure at Columbia University.

But the gear required to really keep radiation at bay isn't practical. "You literally have to be wearing head-to-toe lead to prevent exposure, and that's simply not feasible," says Weinstock.

Lots of research has been done into helping people who have been exposed. High levels of radiation target rapidly dividing cells in the body, especially those in the skin, blood, and gut -- just like chemotherapy for cancer (which is why many people in the field also care for cancer patients). So radiation exposure can kill blood cells, leaving people without a functioning immune system, and cause severe diarrhea and burns. After Chernobyl, doctors experimented with performing bone marrow transplants, but they weren't particularly effective, possibly because of the protocol used or because someone who was so sick that they needed a transplant had also sustained irreparable damage to other organ systems, says Chao. Since Chernobyl, there are new treatments that stimulate blood cell production after cancer treatment. But their value to people exposed to radiation is an open question.

Meanwhile, details are sketchy about the level of risk inside Japan's nuclear plants. The International Atomic Energy Agency (IAEA) shared information from Japanese authorities today that 17 workers "suffered from deposition of radioactive material to their faces," but at low doses. Another worker "suffered from significant exposure" and was taken to an offsite center. Firefighters were also reportedly exposed to radiation.

"Workers accept the risk by the nature of their job, they accept it willingly and hopefully they are paid for it," says Steven Simon, a health physicist at the National Cancer Institute in Bethesda, Maryland. "You don't have the same opportunities to protect them [as the general public], because they agreed to go into a high-risk place."